The San Bernardino shooting happened the same day that Democrats and advocates for doctors held a press conference to urge Congress to lift the ban on gun violence research, which many experts say is critical to understanding why gun violence happens and what we can do to prevent it.

Gun violence in the United States is far more common than in any other developed country.

"The U.S. represents less than 5% of the 7.3 billion global population but accounted for 31% of global mass shooters during the period from 1966 to 2012, more than any other country," according to the Wall Street Journal.

Data from the liberal Center for American Progress suggests that this year gun deaths among young people in the US will finally surpass car accident deaths, which — unlike gun deaths — have been steadily declining:

It's important to note, however, that most gun deaths in the US are not from mass shootings.

As Vox notes, mass shootings in 2013 killed 500 Americans. That's a lot, but it represents only about 4.5% percent of the 11,200 gun homicides that year. And suicides by gun in 2013 killed almost 21,200 Americans.